Hi All, My application team requirement is to able to see the actual client ip address whoever accessing the application instead of BIG IP address as SNAT (Auto map) is enabled. I have read some SOL on it and understand that we can achieve this by iRule & HTTP profile. However, my requirement is to have an iRule as we can take decision whether to add X-Forwarded-For header to client requests. Can anyone please share the iRule script pertaining to this requirement. Thanks in advance, MSK

Hi, if you want to add X-Forwarded-For header you can use: when HTTP_REQUEST { HTTP::header replace X-Forwarded-For [IP::client_addr] }

Hello, You can use the following : when HTTP_REQUEST { if {[HTTP::header exists X-Forwarded-For]}{ HTTP::header replace X-Forwarded-For "[HTTP::header X-Forwarded-For], [IP::client_addr]" } else { HTTP::header insert X-Forwarded-For [IP::client_addr] } }

Hi Vitaliy, Thanks for the quick response. Will this iRule insert X-Forwarded-For header for the client requests which already have it, which shouldn't be the case as per my requirement. -MSK

Hi Yann, Thanks for the quick response. Will this iRule insert X-Forwarded-For header for the client requests which already have it ?? Looking at the script my understanding is it would check if X-Forwarded-For header exists but cannot understand the replace and insert statements of the script. Can you please shed some light on it. -MSK

X-Forwarded-For header

11 Replies

Vitaliy_Savrans
Nacreous
Mar 24, 2016
Hi, if you want to add X-Forwarded-For header you can use:

when HTTP_REQUEST { HTTP::header replace X-Forwarded-For [IP::client_addr] }
- MSK_222682
  Nimbostratus
  Mar 24, 2016
  Hi Vitaliy, Thanks for the quick response. Will this iRule insert X-Forwarded-For header for the client requests which already have it, which shouldn't be the case as per my requirement. -MSK
- Vitaliy_Savrans
  Nacreous
  Mar 24, 2016
  This irule will insert the header if it wasn't present or replace the value.
Yann_Desmarest
Cirrus
Mar 24, 2016
Hello,

You can use the following :

when HTTP_REQUEST { if {[HTTP::header exists X-Forwarded-For]}{ HTTP::header replace X-Forwarded-For "[HTTP::header X-Forwarded-For], [IP::client_addr]" } else { HTTP::header insert X-Forwarded-For [IP::client_addr] } }
- MSK_222682
  Nimbostratus
  Mar 24, 2016
  Hi Yann, Thanks for the quick response. Will this iRule insert X-Forwarded-For header for the client requests which already have it ?? Looking at the script my understanding is it would check if X-Forwarded-For header exists but cannot understand the replace and insert statements of the script. Can you please shed some light on it. -MSK
- Yann_Desmarest
  Cirrus
  Mar 24, 2016
  Hello, The irule provided add the client ip to an existing X- header otherwise, it will add a new one with the clientip. Insert allow you to add a new header. Replace add a new header if there is no existing header with the same name, otherwise it changes the value of an existing x- header
- Vitaliy_Savrans
  Nacreous
  Mar 24, 2016
  about statements https://devcentral.f5.com/wiki/iRules.HTTP__header.ashx
Yann_Desmarest_
Nacreous
Mar 24, 2016
Hello,

You can use the following :

when HTTP_REQUEST { if {[HTTP::header exists X-Forwarded-For]}{ HTTP::header replace X-Forwarded-For "[HTTP::header X-Forwarded-For], [IP::client_addr]" } else { HTTP::header insert X-Forwarded-For [IP::client_addr] } }
- MSK_222682
  Nimbostratus
  Mar 24, 2016
  Hi Yann, Thanks for the quick response. Will this iRule insert X-Forwarded-For header for the client requests which already have it ?? Looking at the script my understanding is it would check if X-Forwarded-For header exists but cannot understand the replace and insert statements of the script. Can you please shed some light on it. -MSK
- Yann_Desmarest_
  Nacreous
  Mar 24, 2016
  Hello, The irule provided add the client ip to an existing X- header otherwise, it will add a new one with the clientip. Insert allow you to add a new header. Replace add a new header if there is no existing header with the same name, otherwise it changes the value of an existing x- header
- Vitaliy_Savrans
  Nacreous
  Mar 24, 2016
  about statements https://clouddocs.f5.com/api/irules/HTTP__header.html

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X-Forwarded-For header

11 Replies

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